1. Field of the Invention
The present invention relates to the field of electrical rotating machines. It pertains to a coil for a dynamo electric machine.
Such a coil is known, for example, from the printed publication U.S. Pat. No. 5,777,417 (FIG. 1) or the printed publication U.S. Pat. No. 4,385,254.
2. Brief Description of the Related Art
The stator coil of a hydro-generator consists of so-called Roebel rods (see, for example, U.S. Pat. No. 5,777,417, which was mentioned at the outset), which are produced from several individual copper sub-conductors. In most instances, a coil consists of an upper layer and a lower layer, thus, two rods, that lie one above the other in an (axial) groove of the sheet metal body of the stator. For the circuitry of the generator coil, the ends of these rods (rod ends) must be bent, both tangentially and radially, in point of fact. These worked rod ends are designated as brackets, or are generally referred to as the head of the coil. The bends in the head of the coil are constructed in accordance with certain guidelines of the requisite electrical clearances and so-called incrementation. In this case, the incrementation designates the number of grooves that a rod “steps across.”
Depicted in FIGS. 1 and 2 is a section of such a coil head 11 of a coil 10 (FIG. 1), which is known from the state of the art, as well as one bent rod end of a single coil rod, in horizontal projection in the direction of the machine's axis. The coil rods, which run in the axial direction in the sheet metal body of the stator, of which two selected coil rods, 12, 14 are depicted in FIG. 1, are connected to one another in pairs in the coil head. This occurs at a connection point 16, which, viewed in the axial direction, lies within a central area between the coil rods, 12, 14. The rod ends 13, 15, which protrude from the sheet metal body of the stator are, in addition, initially bent around in a first tangential bend (17 in FIG. 2) from the axial direction in the direction of the connection point 16 and shortly ahead of the connection point 16, bent back in a second tangential bend (18 in FIG. 2), again in the axial direction. The bent back terminal sections of the rod ends, 13, 15 come, in the process, to lie above one another in the connection point 16.
The middle levels of the coil rods 12, 14, which are drawn as dashes in FIG. 1, which run in the radial direction, and the connection point 16, enclose, in each case, an angle in the process that is all the greater, the greater the aforementioned step width turns out to be. The rod ends 13, 15, as may be seen particularly clearly in FIG. 2, are provided, between the tangential bends 17 and 18, with a continuous, constant curving (bend), so that the configuration of rod ends depicted in FIGS. 1 and 2 can be realized. In the state of the art, these bends are produced by hand by means of a bending tool. This type of shaping, however, has the disadvantage that it takes great effort to perform. In particular, it is necessary to obtain a new bending tool, which is, in most instances, a piecework production, for each generator, since the construction of the coil rods is different every time.